John r



(No Model.)

J. R. COFFMAN.

BRUSH HOLDER. No. 472,435. Patented Apr. 5, 1892.

LIINVENTDR fi: away.

5 Yr 5 m UNITED STATES PATENT OFFICE.

JOHN R. COFFMAN, OF DETROIT, MICHIGAN, ASSIGNOR OF ONE-HALF TO 0. A.BENTON, OF SAME PLACE.

BRUSH-HOLDER.

SPECIFICATION forming part of Letters Patent No. 472,435, dated April 5,1892.

Application filed September 30, 1891. Serial No. 407,214. (No model.)

To all whom it may concern:

Be it known that I, JOHN R. COFFMAN, a citizen of the United States, anda resident of Detroit, in the county of Wayne and State of Michigan,have invented new and useful Improvements in Bl'llSll-IIOltl1S, of whichthe following is a specification.

My invention relates to brush-holders for dynamo-electric machines andmotors,and has for its object to provide more simple and efiicient meansof securing them eifectually and adjustably with devices incapable ofworking loose and such as may be shifted for applying and removing thebrushes, and also for adjusting them without tools and without having tofasten or unfasten any parts, and so as to maintain substantialuniformity of the pressure of the brush on the commutator, all ashereinafter fully described, reference being made to the accompanyingdrawings, in which- Figure 1 is a side elevation of my improvedbrush-holder and a part indicating the commutator of an electricmachine. Fig. 2 is a front elevation of the holder with a part insection. Fig. 3 is a plan view. Fig. 4 is a sectional elevation on line0c :0 of Fig. 3. Fig. 5 is a plan view of the spring-holder andadjusting-lever. Fig. 6 is a sectional elevation on line an 50, Fig. 3,showing an attachment for holding the spring free of the brake.

I employ a brush-holding box or socket a, open at both ends, in whichthe brush 1) may be inserted from the back and projected at the front asuitable distance for making contact with the commutator c and beadjusted forward as it wears away on the commutator, said box or sockethaving a laterally-projecting supporting-arm (Z for mountingit insuitable relation to the commutator for enabling the brush to be held incontact therewith by a spring d. In this case I represent said arm assecured to a part of the frame of the machine or bracket attachedthereto, as e, by a part of the arm extended through an eye of thebracket and clamped to the sides of the bracket by the collar f and adjListing-nut screwing on the arm, suitably threaded for the purpose, withinsulating-plates h between the collar and nut and bracket and also withthe insulating-washers j in the eye of the bracket; but the means ofmounting and insulatin g the said supporting-awn may of course be variedat will.

I mount the spring d, employed to press the brush up to the commutator,on aholderconsisting of a cross-head 7c of a lever Z, arranged betweentwo parallel laterally projecting housings m from one side of thebrush-holder, preferably the lower side, with the ends of said headentering slots n of the housingplates, ranging parallel with thebrush-holding block and having ratchet-notches 0 in the lower walls,said ends of the cross-head being formed in the shape of pawls p toengage in the ratchet-notches and lock the spring-holder anywhere alongthe notches against the thrust of the spring. The spring being fastenedat the end to and several times coiled around the holder is thenextended through the slot (1 in the brush-holding block, extending fromthe rear end forward a suitable distance for the range of the spring inpressing up the brush as it wears away.

It will now be seen from what has been said that by pressing the end ofthe spring bearing against the brush back out of the way the worn-outbrush may be readily removed through the back end of the box and a newone put in, and the spring-holder may be set back in the ratchet at thebeginning of the use of a new brush of full length and be set forwardstep by step in the ratchet as the brush wears short, and thus act withlike tension on the brush during its whole service, and it will be notedthat to shift the spring holder requires only a slight push on the leverZ in the direction of the brush. For shifting it the other way the leverhas to be lifted a little at first to swing the pawls 1) up out of thenotches, when the spring will force it back. Above and below the pawls pthe angles of the cross-head forming the spring-holder are cut away at tto permit the holder to turn for raising the pawls out of the notches.

The brush-holdin g box and its attachments, as the slotted and notchedspring-holderhousin gs and the supporting-arm, are all produced in thecasting, so that no fitting is required except the screw-threads for thecollar and the check-nuts, and thus the holder is made very cheaply.

In Fig. 6 I represent the spring d provided with a ring .9 to hook onthe end of the lever Z and hold it free of the brush and brushholderwhile changing the brush. The solid lines indicate the positions of thespring and lever in the act of connecting them, and the .t'heother maybe detachably applied.

I claim 1. The combination, with the commutatorbrush fixed movably in aslideway to be pressed against the commutator and the spring pressingthe brush therein, of a holder for said spring, also fixed movably in aslideway toward the commutator, and means to adjust said holder andmaintain substantial uniformity of pressure of the brush on thecommutator by the spring, as set forth. 7

2. The combination, with the commutator and the brush, of the socket orbox-holder for the brush, open at the back for receiving the brush andwherein the brush is adapted to 'slide to and from the commutator, aspring adapted to press the. brush against the commutator, a holder forthe spring, and the slotted and notched housings confining thespring-holder, said holder having the pawl ends and being adj ustabiealong the confining-slots, substantially as described. 7

3. The combination, with the commutator and the brush, of the socket orbox-holder for the brush, open at the back for receiving the brush andwherein the brush is adapted to slide to and from the commutator, aspring adapted topress the brush against the commutator, a holder forthe spring, a lever attachment to the holder, and the slotted andnotched housings confining the spring-holder, said holder having thepawl ends and being adjustable along the confining-slots,substantiall yas described.

4. The combination, with the commutator and the brush, of the socket orbox-holder for the brush, open at the back for receiving the brush andwherein the brush is adapted to slide to and from the commutator, aspring adapted to press the brush against the commutator, a holder forthe spring, a lever at tachment to the holder, and the ring forconnecting the spring and lever, substantially as described.

In testimony that I claim the foregoing as my invention I have signed myname, in pres- 6o ence of two witnesses, this 20th day of June,

JOHN R. OOFFMAN. Witnesses:

F. W. PIELFORD, A. B. REMEY.

